Photoelectric musical instrument



Patented May 4, 1943 PBOTOEIECTBIO MUSICAL INSTRUMENT Francis I. Darke, Jr., Moorestown, N. I., udmr America toBadioCo notation of Application March 29, 1941, Serial No. 385,832

8 Claims. (Cl. Ll)

'I'his invention relates to an improvement in photoelectric musical Instruments and, more particularly, to an improvement in the type of photoelectric organs shown, for example, in Toulon Patent 1,948,996.

In this type of instrument, the images of one or more slits are caused to traverse at a predetermined rate a diaphragm carrying the image of the sound wave to be reproduced. As the line of light traverses the image of the sound wave, a greater or less quantity thereof is permitted to pass, and the light is then directed onto a photoelectric cell producing a current which accurately varies in accordance with the sound wave image.

In such devices as heretofore constructed, the control of the timbre of the note was either impossible or inadequate. In the apparatus constructed in accordance with the present invention, the timbre may be controlled in almost endless variety and to any degree desired. This is accomplished by mounting the shutters carrying the wave shape reproductions so that they may be tilted to intercept the light beam to any desired degree.

One object of the invention is to provide an improved electric organ.

Another object of the invention is to provide an electric musical instrument in which any desired tone quality may be secured.

Another object of the invention is to provide an electric musical instrument in which the several partials involved in the reproduction of a note may be chosen at will. y

Other and incidental objects of the invention will be apparent to those skilled in the art from the following speciilcation and the accompanying drawing in which:

Figure 1 is a schematic perspective view of the apparatus,

Figure 2 is an elevation of the bank of overtone selectors indicated at I in Figure 1, and

Figure 3is an end view of the overtone selectors of Figure 2 indicating their manner of operation.

Referring to Figure 1, light from a source 9 is directed by the condenser lens II through disc I2. This disc I2 is provided with a number of series of radial slots corresponding in relative number with the-notes in an octave or greater portion of the range of the apparatus. Duplicate apparatuses may be provided for a range of any number of octaves or frequency changing devices may be used to produce the other frequencies.

Light passing through the slits in the disc i2 is selected according to the desired notes by the shutters in the shutter bank I3 which are controlled by the keys I4 in any conventional manner such as shown in U. S. Patent No. 1,848,222 of March 8. 1932. A Light passing through the slim in thedisc I2isfocused bythelens IIuponthe wave images in the box Il. The lens I5 is prei'- erably cylindrical so that each slit in the disc I2 for which the shutter is opened produces a linear image the entire height of all the wave images of the box I0 and the spacing of the slits in the disc I2 and the shutter lengths are so arranged that, as one slit image leaves the wave shape images, the next slit image of the same frequency is Just entering the wave shape images from the opposite side. Light passing through the wave shape images is directed by the lenses I1 and I8 onto the photocell I9. The output o! the photocell is amplified in the usual manner by an electronic amplifier and reproduced through a conventional loudspeaker or bank of loudspeakers.

'I'he wave shape images shown in'Figure 2 consist of a series of shutters 20, 2|, 22, 23, 2l and 25, which vary either in outline or in transparency in accordance with the contours indicated. 'I'he shutter 20, for example, would determine the fundamental of the note to be reproduced. The shutter 2| would determine the first overtone an octave higher. The shutter 22 would determine the second overtone an octave and a fifth higher. The shutter 23 determines the second overtone which is indicated as two octaves higher. The shutter 24 would determine the fourth overtone which would be two octaves and a third higher while the shutter 25 would determine the sixth overtone two octaves and a ifth higher. It will be apparent that the overtones determined by these shutters need not be in the arrangement indicated but that some of these overtones may be omitted or others substituted or practically any desired arrangement or number of overtones may be used. Further, the tones of the keyboard may be determined by one of the higher frequencies of the shutter bank, as, for example, by the shutter 22, while the shutters 20 and 2I might be controlled by a bass coupler.

The several shutters are mounted as shown in Figure 3 so that they may be tilted at any desired angle. Ii' one of these shutters is tilted so that its plane is parallel to the direction of travel oi the light beam, it will have no effect on the light drawing, but that these shutters may have any other desired contour.` For example, one of these shutters may have substantially a sine wave configuration to represent the fundamental tone and others may represent tones of entirely different quality as, for example, those produced by photographic recordings of various instruments whose tone qualities it may be desired to introduce as disclosed in U. S. Patent No. 1,998,461 of April 23, 1935.

Although the shutters 2D 25 are shown as individually lactuated by pull rods 30 connected to individual stops 3|, it will be apparent to those skilled in the art that these pull rods may be mechanically interconnected in any desired manner so that the operation of the onestop will simultaneously operate two or more of the shutters either to the same extent or in predetermined relation to each other.

I claim as my invention:

l. Tone control mechanism for an electric musical instrument of the type wherein a moving beam of light scans a stationary wave image and is thereafter directed to a photoelectric cell including a plurality of wave image shutters to produce diiierent tones, and means for selectively adjusting each of said shutters to intercept a greater or smaller proportion ofthe light beam to vary the amplitude of each respective tone, the

greater the amount of light transmitted to said cell, the smaller the degree of modulation of said light beam and the amplitude of the respective tone.

2. Tone control mechanism for an electric musical instrumentl of the type wherein a moving beam of light scans a stationary Wave image and is thereafter directed to a photoelectric cell including a plurality of variable area wave image shutters to produce diierent tones, and means for selectively adjusting'each of said shutters about the base line of the image to intercept a greater or smaller proportion of the light beam to vary the amplitude of each respective tone, the greater Vthe amount of light transmitted to said cell, the smaller the degree of modulation of `said light beam and the amplitude of each respective tone.

3.- Tone control mechanism for an electric musical instrument of the type wherein a moving beam of light scans a stationary wave image-and is thereafter directed to a photoelectric cell including a plurality of wave image shutters to produce diiierent tones, each shutter being adjustable about an axis parallel with the base line of the wave images to vary the amplitude of said tones, and means for selectively adjusting said shutters to each intercept a greater or smaller proportion of the light beam to vary the amplitude of each respective tone, the greater the amount of light transmitted to said cell, the smaller the degree of modulation of said light beam and the smaller the amplitude of each respective tone.

4. Tone control mechanism for an electric mu- `sical instrument of the type wherein a beam of light scans a stationary wave image and is thereafter directed to a photoelectric cell including a plurality of variable area wave image shutters to produce different tones, each shutter being adjustable about an axis parallel with the base line of the wave image to vary the amplitude of the respective tones produced thereby, and means for selectively adjusting said shutters to each intercept a greater or smaller proportion of the light beam, the greater the amount of said light beam transmitted to said cell, the smaller the degree of modulation of the light beam and the smaller the respective tone amplitude.

5. An electric musical instrument including a light source, scanning means defining light slits corresponding to notes, shutters deiining areas corresponding to wave shapes, means for directing light from said scanning means to said shutters, means for directing light passing said shutters to a photoelectric means to produce tones corresponding with the wave image of each shutter, and means for selectively adjusting the proportion of the light beam intercepted by each of said shutters, the greater the amount of light transmitted to said photoelectric means, the' smaller the degree of modulation of said light by said shuttersr andthe smaller the respective.

tone amplitudes.

6. An electric musical instrument including a light source, scanning means defining light slits corresponding to notes, shutters defining areas corresDOnding to variable area wave shapes, means for directing light from said scanning means to said shutters, means for directing light passing the said shutters to a photoelectric means to produce tones corresponding with the wave shapes of said shutters, and means for selectively adjusting the proportion of the light beam intercepted by each of said shutters, the greater the amount of light transmitted to said photoelectric means the smaller the degree of modulation of said light by said shutters and the smaller the respective tone amplitude.

7. An electric musical instrument including a light source, scanning means dening light slits corresponding to notes, shutters dening areas corresponding to wave shapes, means for directing light from said scanning means to said shutters, means for directing light passing said shutters to a photoelectric means to create different tones, and means for selectively adjusting each of said shutters about an axis parallel to its own plane and perpendicular to the plane dened by the scanning beam for determining the proportion of the light beam intercepted by each of said shutters, the greater the amount of light transmitted to said photoelectric means, the smaller the degree of modulation of said light by said shutters and the smaller the respective tone amplitudes.

8. An electric musical instrument including a light source, scanning means defining light slits corresponding to notes, variable shutters deiining areas corresponding to wave shapes, means for directing light from said scanning means to .said shutters, means for directing light passing said shutters to a photoelectric means to create different tones, and means for selectively adjusting each of said shutters about an axis parallel to its own plane and perpendicular to the plane defined by the scanning beam for determining the proportion of the light beam intercepted by each of said shutters, the greater the amount of light transmitted to 'said photoelectric means, the smaller the degree of modulation of said light by said shutters and the smaller the respective tone amplitudes.

FRANCIS J. DARKE, JR. 

